Head mounted display systems have been developed for a number of different applications including use by aircraft pilots and for simulation. Head mounted displays are generally limited by their resolution and by their size and weight. Existing displays have relatively low resolution and are positioned at a relatively large distance from the eye. Of particular importance, is to keep the center of gravity of the display from extending upward and forward from the center of gravity of the head and neck of the wearer, where it will place a large torque on the wearer's neck and may bump into other instruments during use. There is a continuing need to present images to the wearer of a helmet mounted display in a high-resolution format similar to that of a computer monitor. The display needs to be as non-intrusive as possible, leading to the need for a lightweight and compact system.
Head mounted displays can also utilize eye tracking systems in flight control, flight simulation and virtual imaging displays. Eye control systems generate information based on the position of the eye with respect to an image on a display. This information is useful for a variety of applications. It can be used to enable the viewer to control "hands-free" movement of a cursor, such as a cross-hair on the display.
Apparatus for detecting the orientation of the eye or determining its line-of-sight (LOS) are called occulometers or eye trackers and are well known in the art. (See for example U.S. Pat. Nos. 4,109,145, 4,034,401 and 4,028,725).